Geometry: shape, size, aspect ratio and orientation Flow Type: forced, natural, laminar, turbulent, internal, external Boundary: isothermal (Tw = constant) or isoflux (q̇w = constant) Fluid Type: viscous oil, water, gases or liquid metals Properties: all properties determined at film temperature Tf = (Tw + T∞)/2 Note: ρ and ν ∝ 1/Patm ⇒ see Q12-40 density: ρ ((kg/m) specific heat: Cp (J/kg ·K) dynamic viscosity: μ, (N · s/m) kinematic viscosity: ν ≡ μ/ρ (m/s) thermal conductivity: k, (W/m ·K) thermal diffusivity: α, ≡ k/(ρ · Cp) (m/s) Prandtl number: Pr, ≡ ν/α (−−) volumetric compressibility: β, (1/K)

Convection Heat Transfer

Thermal effects in packaging high power light emitting diode arrays

The experimental and numerical investigation of a grooved vapor chamber

Thermal response of a flat heat pipe sandwich structure to a localized heat flux

The experimental investigation on thermal performance of a flat two-phase thermosyphon

Power devices such as IGBTs dissipate very large heat flux densities. Therefore the thermal environment is a main issue in their performance and reliability. In order to improve heat transfer, materials with high thermal conductivity seem to be very useful. Because of their high cost, we suggest replacing them with a groove wick and sintered metal powder wick heat pipes. Thermal simulations are provided to show the interest of these structures in power electronics. Heat spreaders composed of heat pipe or plain material are compared. A 40% decrease of the thermal resistance between the heat source and the ambient is expected. Then an experimental study on a brass-water heat pipe is described. Results are compared with thermal simulations.

On the use of flat heat pipes as thermal spreaders in power electronics cooling

Currently the thermal losses of power electronic devices like IGBTs are increasing. At the same time, their sizes are decreasing. Consequently heat sinks have to dissipate very large heat flux densities. Therefore the thermal environment is a main issue in their performance and reliability. In order to improve heat transfers, materials with high thermal conductivity seem very interesting. Because they are expensive, we propose to replace them with heat pipes. Firstly an experimental study is described in order to show the interests of heat pipes in power electronics cooling. Then thermal simulations on copper/water and silicon/water heat pipes are provided. Thanks to them, heat spreaders made with heat pipes and heat spreaders made with plain material are compared. A 40% decrease of the thermal resistance between the heat source and the ambient is expected.

http://ieeexplore.ieee.org/iel5/8075/22360/01044091.pdf

Thermal analysis of thermal spreaders used in power electronics cooling

https://www.j3ea.org/articles/j3ea/pdf/2003/03/j3ea2003610.pdf

A. Bricard

Papers

On the use of flat heat pipes as thermal spreaders in power electronics cooling

Thermal analysis of thermal spreaders used in power electronics cooling

Apport de la microthermie pour le refroidissement des systèmes